Birds of a feather usually refers to people who have a lot in common with one another. So the quote probably is linked to the idea that when people only hang out with others who are like them and share their views they'll never learn anything new.
if you only associate with people just like you you wont experience much new stuff.
In the nursery rhyme "Birds of a Feather," the birds will flock together.
Birds of a feather flock together, but all birds cannot fly.
Birds of a feather are said to "flock together".
"Birds of a feather flock together."
Because they are limited by the collective intelligence of only their flock.
Robert Half
Birds of feather flock together.
Yes, "Birds of a feather flock together".
Big Break Dominican Republic - 2010 Birds of a Feather Flock Together was released on: USA: 2010
Scoundrels - 2010 Birds of a Feather Flock Together 1-6 was released on: USA: 1 August 2010
Opposites attract
Birds with the same feather flock together means that like people tend to associate with each other. Those that like sports tend to hang together and those that like video games can be found together.